A multiphased analysis in an animal model of the effects of non- anticoagulant heparin fragments and heparin binding growth factor-I (HBGF-I), was undertaken in three parts using a balloon injury model. The three parts of the analysis include: a) study of the pharmacokinetics and distribution of HBGF-1 in a rat; b) determination of binding characteristics of HBGF-I to intact and injured rat vasculature, and c) examination of the ability of HBGF-I to accelerate endothelial regeneration and act synergistically with heparin. HBGF-I causes acceleration of endothelial cell growth in vitro which is enhanced by heparin. The data demonstrate a rapid HBGF-I half-life which is prolonged by heparin. Heparin enhances HBGF-I binding to all organs measured except kidney, which is decreased. Saturation of binding occurs at an approximate blood concentration of 10 ng/ml. Heparin fragments with HBGF-I appear to increase endothelial regrowth into denuded rat carotid artery approximately 2-fold.